<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <script>
        var today=new Date();
        var hour=today.getHours();
        var greet=greeting(hour);
        document.write(greet);
        function greeting(hour){
            if(hour < 6){
                return "凌晨好！"
            }
            else if (hour < 9){
                return "早上好！";
            }
            else if (hour < 12){
                return "上午好！";
            }
            else if (hour < 14){
                return "中午好！";
            }
            else if (hour < 17){
                return "下午好！";
            }
            else if (hour < 19){
                return "傍晚好！";
            }
            else if (hour < 22){
                return "晚上好！";
            }
            else {
                return "夜里好！";
            }
        }
    </script>
</body>
</html>